Acrylic alkoxy silane monomer and solid electrolyte derived by the polymerization thereof

ABSTRACT

This invention is directed to a novel acrylic alkoxy substituted silane and to a single phase solid solvent-containing electrolyte having recurring units derived from such silane incorporated within the solid polymeric matrix of the solid electrolyte. A novel electrolytic cell that incorporates the subject electrolyte also is provided. The specific molecular structure exhibited by such solid polymeric matrix is believed to advantageously facilitate the positioning of an inorganic ion salt and solvent between adjacent polymeric molecules during service within the solid electrolyte.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is directed to a novel acrylic alkoxy substituted silaneas well as to solid electrolytes derived through the polymerization ofthe same.

This invention is further directed a solid electrolytic cell (battery)containing an anode, a cathode and a single phase solid electrolytecomprising a solid polymeric matrix containing recurring units derivedfrom the acrylic alkoxy substituted silane, an inorganic ion salt, and asolvent.

2. State of the Art Electrolytic cells containing an anode, a cathodeand a solid, solvent-containing electrolyte are known in the art and areusually referred to as "solid batteries". These cells offer a number ofadvantages over electrolytic cells containing a liquid electrolyte(i.e., "liquid batteries") including improved safety features.

The solid, solvent-containing electrolyte employed in such solidbatteries has heretofore contained either an inorganic matrix or anorganic polymeric matrix as well as a suitable inorganic ion salt.Because of their expense and difficulty in forming into a variety ofshapes, inorganic non-polymeric matrices are, however, not preferred andthe art typically has employed a solid electrolyte containing an organicor inorganic polymeric matrix.

Suitable organic polymeric matrices are well known in the art and aretypically organic homopolymers obtained by the polymerization of asuitable organic monomer as described, for example, in U.S. Pat. No.4,908,283 or copolymers obtained by polymerization of a mixture oforganic monomers. Suitable organic monomers include, by way of example,polyethylene oxide, polypropylene oxide, polyethyleneimine,polyepichlorohydrin, polyethylene succinate, and an acryloyl-derivatizedpolyalkylene oxide containing an acryloyl group of the formula CH₂═CR'C(O)O--where R' is hydrogen or lower alkyl having from 1 to 6 carbonatoms.

Additionally, suitable organic monomers preferably contain at least oneheteroatom capable of forming donor acceptor bonds with inorganiccations (e.g., alkali ions). When polymerized, these compounds form apolymer suitable for use as an ionically conductive matrix in a solidelectrolyte.

The solid electrolytes also contain a solvent (plasticizer) which isadded to the matrix primarily in order to enhance the solubility of theinorganic ion salt in the solid electrolyte and thereby to increase theconductivity of the electrolytic cell. In this regard, the solventrequirements of the solvent used in the solid electrolyte have been artrecognized to be different from the solvent requirements in liquidelectrolytes. For example, solid electrolytes require a lower solventvolatility as compared to the solvent volatilities permitted in liquidelectrolytes.

Suitable solvents well known in the art for use in such solidelectrolytes include, by way of example, propylene carbonate, ethylenecarbonate, γ-butyrolactone, tetrahydrofuran, glyme (dimethoxyethane),diglyme, tetraglyme, dimethylsulfoxide, dioxolane, sulfolane, and thelike.

Heretofore, the solid, solvent-containing electrolyte has typically beenformed by one of two methods. In one method, the solid matrix is firstformed and then a requisite amount of this material is dissolved in avolatile solvent. Requisite amounts of the inorganic ion salt and theelectrolyte solvent (a glyme and the organic carbonate) are then addedto the solution. This solution is then placed on the surface of asuitable substrate (e.g., the surface of a cathode) and the volatilesolvent is removed to provide for the solid electrolyte.

In the other method, a monomer or partial polymer of the polymericmatrix to be formed is combined with appropriate amounts of theinorganic ion salt and the solvent. This mixture is then placed on thesurface of a suitable substrate (e.g., the surface of the cathode) andthe monomer is polymerized or cured (or the partial polymer is thenfurther polymerized or cured) by conventional techniques (e.g. heat,ultraviolet radiation, electron beams, etc.) so as to form the solid,solvent-containing electrolyte.

While the electrolytes described above perform adequately in theirintended role, there is need for improvement in several areas. First,the conductivity of the electrolyte could advantageously be increased.Cumulative capacity of a solid battery is the summation of the capacityof the battery over each cycle (charge and discharge) in a specificcycle life.

Second, the electrolyte must be compatible with the typically usedinorganic ion salt incorporated into the polymer matrix to aid inconductivity. The inorganic ion salt, which usually contains Li ion butwhich can contain other metal ions as discussed hereinafter, must besoluble in the electrolyte to form a one-phase system. Hence the amountof salt which can be incorporated in the electrolyte is limited by thesalt's saturation concentration. By providing an electrolyticenvironment in which the salt is more soluble, more of the salt can beincorporated and hence conductivity can be increased.

Third, the solid polymeric matrix must have a certain degree offlexibility and swellability in order to function properly in the cell.If the cross-linking density is too high, the resulting polymer networkis very tight, resulting in minimal flexibility and swellability.

SUMMARY OF THE INVENTION

An acrylic alkoxy substituted silane of the specified chemical structurecan be polymerized and is capable of being incorporated into thepolymeric backbone of a solid polymeric matrix that is useful in theformation of an electrolytic cell. The presence of recurring unitsderived from such acrylic alkoxy silane in the solid polymeric matrixbecause of its specific molecular structure advantageously facilitatesthe positioning of the inorganic ion salt and solvent among thepolymeric molecules during service as a solid polymeric matrix. Theorganic monomer of this invention is represented by Formula I: ##STR1##where z is 3 to 10 (preferably 4 to 6), and R₁, R₂, and R₃ areindependently selected from the group consisting of (a) --Y--CH₂CH₂)_(x) H where x is an integer of 1 to 20 (preferably 3 to 10), Y isO, S, NH, or NR where R is an alkyl group having 1 to 10 carbon atoms(preferably 1 to 4 carbon atoms), (b) an alkyl substituent having 1 to 6carbon atoms (preferably 1 to 4 carbon atoms), (c) an alkoxy grouphaving 1 to 6 carbon atoms (preferably 1 to 4 carbon atoms), (d) --O--R₄--O)_(p) R₅ where R₄ is an alkylene group having 1 to 4 carbon atoms(preferably 1 to 2 carbon atoms), R₅ is an alkyl substituent having from1 to 4 carbon atoms (preferably 1 to 2 carbon atoms), and p is aninteger from 1 to 4 (preferably 3 to 4), (e)--SR₆ where R₆ is an alkylsubstituent having from 1 to 6 carbon atoms (preferably 1 to 4 carbonatoms), (f)--NH₂, (g)--NHR₇ where R₇ is an alkyl substituent having 1 to6 carbon atoms (preferably 1 to 4 carbon atoms), (h)--NR₈ R₉ where R₈and R₉ are independently chosen from alkyl substituents having 1 to 6carbon atoms (preferably 1 to 4 carbon atoms), ##STR2##

When polymerized alone or when copolymerized with other monomers, suchas those previously discussed, the acrylic alkoxy substituted silaneforms a polymeric structure that is well-suited for serving as the solidpolymeric matrix component of a solid electrolyte when combined with aninorganic ion salt and a solvent. Accordingly, the present inventionfurther is directed to a single phase, solid, solvent-containingelectrolyte which comprises:

a solid polymeric matrix

an inorganic ion salt; and

a solvent;

wherein said solid polymeric matrix is obtained by polymerizing orcopolymerizing an organic monomer represented by Formula I: ##STR3##where z is 3 to 10, and R₁, R₂, and R₃ are independently selected fromthe group consisting of (a) --Y--CH₂ CH₂)_(x) H where x is an integer of1 to 20, Y is O, S, NH, or NR where R is an alkyl group having 1 to 10carbon atoms, (b) an alkyl substituent having 1 to 6 carbon atoms, (c)an alkoxy group having 1 to 6 carbon atoms, (d) --O--R₄ --O)_(p) R₅where R₄ is an alkylene group having 1 to 4 carbon atoms, R₅ is an alkylsubstituent having from 1 to 4 carbon atoms, and p is an integer from 1to 4, (e)--SR₆ where R₆ is an alkyl substituent having from 1 to 6carbon atoms, (f)--NH₂, (g)--NHR₇ where R₇ is an alkyl substituenthaving 1 to 6 carbon atoms, (h)--NR₈ R₉ where R₈ and R₉ areindependently chosen from alkyl substituents having 1 to 6 carbon atoms,##STR4## where y is 3 to 10, and R₁₁ is H or CH₃.

In yet another aspect of the present invention an electrolytic cell isprovided which comprises:

(i) an anode comprising a compatible anodic material;

(ii) a cathode comprising a compatible cathodic material; and

(iii) interposed therebetween a single phase, solid, solvent-containingelectrolyte which comprises: a solid polymeric matrix; an inorganic ionsalt; and a solvent;

wherein said solid polymeric matrix is obtained by polymerizing orcopolymerizing an organic monomer represented by the Formula I: ##STR5##where z is 3 to 10, and R₁, R₂, and R₃ are independently selected fromthe group consisting of (a) --Y--CH₂ CH₂)_(x) H where x is an integer of1 to 20, Y is O, S, NH, or NR where R is an alkyl group having 1 to 10carbon atoms, (b) an alkyl substituent having 1 to 6 carbon atoms, (c)an alkoxy group having 1 to 6 carbon atoms, (d) --O--R₄ --O)_(p) R₅where R₄ is an alkylene group having 1 to 4 carbon atoms, R₅ is an alkylsubstituent having from 1 to 4 carbon atoms, and p is an integer from 1to 4, (e)--SR₆ where R₆ is an alkyl substituent having from 1 to 6carbon atoms, (f)--NH₂, (g)--NHR₇ where R₇ is an alkyl substituenthaving 1 to 6 carbon atoms, (h)--NR₈ R₉ where R₈ and R₉ areindependently chosen from alkyl substituents having 1 to 6 carbon atoms,##STR6## where y is 3 to 10, and R₁₁ is H or CH₃.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As noted above, this invention is directed to solid, solvent-containingelectrolytes which employ the specific solid, polymeric matrix derivedfrom the acrylic alkoxy substituted silane monomer. Various terms usedherein are defined below.

Definitions

As used herein, the specified terms have the following meanings.

The term "solid polymeric matrix" refers to an ion-conductive matrixformed by polymerizing an organic monomer containing at least oneheteroatom capable of forming donor acceptor bonds with inorganiccations derived from inorganic ion salts under conditions such that theresulting polymer is useful in preparing solid electrolytes. Solidpolymeric matrices are well known in the art and are described, forexample, in U.S. Pat. Nos. 4,908,283 and 4,925,751 both of which areincorporated herein by reference in their entirety. The solid polymericmatrix of the present invention includes repeating units derived fromthe acrylic alkoxy substituted silane monomer as set forth in detailherein.

The term "inorganic ion salt" refers to any inorganic salt which issuitable for use in a solid electrolyte. Representative examples arealkali metal and ammonium salts of less mobile anions of weak baseshaving a large anionic radius. Examples of such anions are I⁻, Br⁻,SCN,⁻ ClO₄ ⁻, BF₄ ⁻, PF₆ ⁻, AsF₆ ⁻, CF₃ COO⁻, CF₃ SO₃ ⁻, etc. Specificexamples of suitable inorganic ion salts include LiClO₄, LiI, LiSCN,LiBF₄, LiAsF₆, LiCF₃ SO₃, LiPF₆, NaI, NaSCN, KI, CsSCN and the like. Theinorganic ion salt preferably contains at least one atom selected fromthe group consisting of Li, Na, K, Cs, Rb, Ag, Cu and Mg. Preferredinorganic ion salts are LiPF₆, LiClO₄, NaClO₄, LiCF₃ SO₃, and LiBF₄.

The term "electrolyte solvent" refers to the solvent (i.e., plasticizer)added to the electrolyte and/or the cathode for the purpose ofsolubilizing the inorganic ion salt. Preferred are the various polaraprotic solvents. Examples of polar aprotic solvents useful in theinvention are polar solvents such as propylene carbonate, ethylenecarbonate, butylene carbonate, γ-butyrolactone, tetrahydrofuran,2-methyltetrahydrofuran, and 1,3-dioxolane.

If the solid polymeric matrix is formed by radiation polymerization ofthe monomer of Formula I, then the solvent should be radiation inert atleast up to the levels of radiation employed. If the solid polymericmatrix is formed by thermal polymerization, the solvent should bethermally inert at least up to the temperatures of thermalpolymerization. Additionally, the solvent should not scavenge freeradicals.

A particularly preferred solvent is a mixture of an organic carbonate(e.g., propylene carbonate) and triglyme as disclosed in U.S. patentapplication Ser. No. 07/918,509, filed Jul. 22, 1992, entitled "SOLID,SOLVENT-CONTAINING ELECTROLYTES AND ELECTROLYTIC CELLS PRODUCEDTHEREFROM" which application is incorporated herein by reference in itsentirety.

The term "cured" or "cured product" refers to the treatment of themonomer of Formula I above (or a partial polymer thereof) underpolymerization conditions (including cross-linking) so as to form asolid polymeric matrix. Suitable polymerization conditions for theacrylic portion of the monomer are well known in the art and include byway of example, heating the monomer, irradiating the monomer with UVlight, electron beams, etc.

The term "electrolytic cell" refers to a composite containing an anode,a cathode, and an ion-conducting electrolyte interposed therebetween.

The anode is typically comprised of a compatible anodic material whichis any material which functions as an anode in a solid electrolyticcell. Such compatible anodic materials are well known in the art andinclude, by way of example, lithium, lithium alloys, such as alloys oflithium with aluminum, mercury, manganese, iron, zinc, and the like, andintercalation based anodes such as carbon, tungsten oxides, and thelike.

The cathode is typically comprised of a compatible cathodic material(i.e., insertion compounds) which is any material which functions as apositive pole in a solid electrolytic cell. Such compatible cathodicmaterials are well known in the art and include, by way of example,manganese oxides, molybdenum oxides, vanadium oxides, sulfides oftitanium, molybdenum and niobium, chromium oxides, copper oxides,lithiated cobalt oxides, lithiated manganese oxide, and the like. Theparticular compatible cathodic material employed is not critical.

In one preferred embodiment, the compatible cathodic material is mixedwith an electroconductive material including, by way of example,graphite, powdered carbon, powdered nickel, metal particles, conductivepolymers (i.e., characterized by a conjugated network of double bondslike polypyrrole and polyacetylene), and the like, and a polymericbinder to form under pressure a positive cathodic plate.

In another preferred embodiment, the cathode is prepared from a cathodepaste which comprises from about 35 to 65 weight percent of a compatiblecathodic material; from about 1 to 20 weight percent of anelectroconductive agent; from about 0 to 20 weight percent ofpolyethylene oxide having a number average molecular weight of at least100,000; from about 10 to 50 weight percent of the electrolyte solvent;and from at least about 5 weight percent to 30 weight percent of a solidpolymeric matrix which includes the monomer of Formula I above. (Allweight percents are based on the total weight of the cathode.)

The cathode paste is typically spread onto a suitable support such as acurrent collector and then cured by conventional methods to provide fora solid positive cathodic plate. The cathode (excluding the support)generally has a thickness of from about 20 to about 150 microns.

Current collectors are well known in the art some of which arecommercially available. A particularly preferred current collector isdescribed hereafter. The current collectors are preferably attached tothe surface of the cathode not facing the electrolyte but can also beattached to the anode. When the current collector is attached to thecathode, the cathode is interposed between the electrolyte and thecurrent collector.

In still another preferred embodiment, the electrolyte solvent and thecathode solvent are identical.

Methodology

Methods for preparing solid electrolytes are well known in the art. Thisinvention, however, utilizes a particular monomer in the preparation ofsolid polymeric matrix of the solid electrolyte, wherein the monomer isan acrylic alkoxy silane represented by Formula I: ##STR7## where z is 3to 10, and R₁, P₂, and R₃ are as defined herein.

The synthesis of the monomer of Formula I above can be carried out byfirst reacting an appropriate halosilane (typically a chlorosilane)having the requisite R₁, R₂, or R₃ substituents with an alkyl diol ofthe specified chain length. The reaction typically results in theevolution of hydrogen halide (e.g., HCl). The substituted silane of theformula: ##STR8## can next be reacted with acryloyl chloride with theevolution of HCl to form the acrylic alkoxy substituted silane ofFormula I. Alternatively, a starting material of the formula: ##STR9##can be reacted with a compound of the formula: ##STR10## with theevolution of HCl to form the acrylic alkoxy substituted silane ofFormula I.

Representative preferred acrylic alkoxy substituted silanes of Formula Iare those wherein each of R₁, R₂, and R₃ are methoxy, ##STR11##

A solid polymeric matrix may be formed that contains from approximately1 to 100 mole percent of recurring units derived from the acrylic alkoxysubstituted silane of Formula I, and preferably approximately 25 to 75mole percent of such units. Preferred units that are copolymerized withthe acrylic alkoxy substituted silane are the low molecular weightacrylates having a molecular weight less than approximately 900 (e.g.,1,6-hexanediol diacrylate, Bisphenol diacrylate, hexyl acrylate, etc.).

In one embodiment, the solid, solvent-containing electrolyte is preparedby combining a compound of Formula I or a mixture of compounds ofFormula I and optionally other monomers or partial polymers with aninorganic ion salt and the electrolyte solvent. The resultingcomposition is then uniformly coated onto a suitable substrate (e.g.,aluminum foil, a glass plate, a lithium anode, a cathode, etc.) by meansof a roller, a doctor blade, a bar coater, a silk screen or spinner toobtain a film of this composition or its solution. In some cases, it maybe necessary to heat the composition so as to provide for a coatablematerial.

Preferably, the amount of material coated onto the substrate is anamount sufficient so that after curing, the resulting solid,solvent-containing electrolyte has a thickness of no more than about 250microns (μm). Preferably, the solid, solvent-containing electrolyte hasa thickness of from about 25 to about 100 microns. The optimum thicknesschosen is a function of the particular application and can readily bedetermined by one skilled in the art.

The electrolyte composition typically comprises from about 5 to about 25weight percent of an inorganic ion salt based on the total weight of theelectrolyte, preferably, from about 10 to about 20 weight percent, andeven more preferably about 15 weight percent.

Where one or more of R₁, R₂, and R₃ contain an unsaturated terminalgroup, the compound of Formula I is readily capable of cross-linking thepolymer chain.

The electrolyte composition typically comprises from about 40 to about80 weight percent solvent based on the total weight of the electrolyte,preferably from about 60 to about 80 weight percent, and even morepreferably about 70 weight percent.

The solid electrolyte composition typically comprises from about 5 toabout 30 weight percent of the polymer that includes units derived fromthe compound of Formula I based on the total weight of the electrolyte.

In a preferred embodiment, the electrolyte composition further comprisesa small amount of a film-forming agent. Suitable film-forming agents arewell known in the art and include, by way of example, polypropyleneoxide, polyethylene oxide, copolymers thereof, and the like, having anumber average molecular weight of at least about 100,000. Preferably,the film-forming agent is employed in an amount of about 1 to about 10weight percent and more preferably from about 2 to about 4 weightpercent based on the total weight of the electrolyte composition.

The composition is cured by conventional methods to form a solid film.For example, suitable curing methods include heating, irradiation withUV radiation, irradiation with electron beams (EB), etc. When thecomposition is cured by heating or UV radiation, the compositionpreferably contains an initiator. For example, when curing is byheating, the initiator is typically a peroxide such as benzoyl peroxide,methyl ethyl ketone peroxide, t-butyl peroxypyvarate, diisopropylperoxycarbonate, and the like. When curing is by UV radiation, theinitiator is typically benzophenone, Darocur 1173 (Ciby Geigy, Ardlesy,N.Y.), and the like.

The initiator is generally employed in an amount sufficient to catalyzethe polymerization reaction. Preferably, the initiator is employed at upto about 1 weight percent based on the weight of the solidmatrix-forming monomer.

When curing is by EB treatment, an initiator is not required.

The resulting solid electrolyte is a homogeneous, single phase materialwhich is maintained upon curing, and which does not readily separateupon cooling to temperatures below room temperature. See, for example,U.S. Pat. No. 4,925,751 which is incorporated herein by reference in itsentirety.

Additionally, it is desirable to avoid the use of any protic materialswhich will be incorporated into the battery. For example, most of theprotic inhibitors for preventing premature monomer polymerization (e.g.,protic inhibitors found in di- and triacrylate monomers) employed withthe monomers are preferably removed prior to formation of the solidmatrix (e.g., the cathode and/or electrolyte) by contact with ainhibitor remover such as Inhibitor Remover available as product No.31,133-2 from Aldrich Chemical, Milwaukee, Wis. Such proceduresgenerally will lower the inhibitor concentration to less than about 50ppm.

In a preferred embodiment, the process of forming an electrolytic cellcomprises the steps of coating the surface of a cathode with acomposition comprising requisite amounts of a compound of Formula I or amixture of compounds of Formula I, an inorganic ion salt and theelectrolyte solvent. The composition is then cured to provide for asolid electrolyte on the cathodic surface. The anode (e.g., a lithiumfoil) is then laminated to this composite product in such a way that thesolid electrolyte is interposed between the lithium foil and thecathodic material.

This process can be reversed so that the surface of a anode is coatedwith a composition comprising requisite amounts of a compound of FormulaI or a mixture of compounds of Formula I, an inorganic ion salt and theelectrolyte solvent. The composition is then cured to provide for asolid electrolyte on the anodic surface. The cathode is then laminatedto this composite product in such a way that the solid electrolyte isinterposed between the lithium foil and the cathodic material.

Methods for preparing solid electrolytes and electrolytic cells are alsoset forth in U.S. Pat. Nos. 4,830,939 and 4,925,751 which areincorporated herein by reference in their entirety.

EXAMPLE

The following example is offered to illustrate the present invention andshould not be construed in any way as limiting its scope.

A solid electrolytic cell is prepared by first preparing a cathodicpaste which is spread onto a current collector and is then cured toprovide for the cathode. An electrolyte solution is then placed onto thecathode surface and is cured to provide for the solid electrolytecomposition. Then, the anode is laminated onto the solid electrolytecomposition to provide for a solid electrolytic cell. The specifics ofthis construction are as follows:

A. The Current Collector

The current collector employed is a sheet of aluminum foil having alayer of adhesion promoter attached to the surface of the foil whichwill contact the cathode so as to form a composite having a sheet ofaluminum foil, a cathode and a layer of adhesion promoter interposedtherebetween.

Specifically, the adhesion promoter layer is prepared as a dispersedcolloidal solution in one of two methods. The first preparation of thiscolloidal solution for this example is as follows:

84.4 weight percent of carbon powder (Shawinigan Black™--available fromChevron Chemical Company, San Ramon, Calif.)

337.6 weight percent of a 25 weight percent solution of polyacrylic acid(a reported average molecular weight of about 90,000, commerciallyavailable from Aldrich Chemical Company--contains about 84.4 gramspolyacrylic acid and 253.2 grams water)

578.0 weight percent of isopropanol.

The carbon powder and isopropanol are combined with mixing in aconventional high shear colloid mill mixer (Ebenbach-type colloid mill)until the carbon is uniformly dispersed and the carbon particle size issmaller than 10 microns. At this point, the 25 weight percent solutionof polyacrylic acid is added to the solution and is mixed forapproximately 15 minutes. The resulting mixture is pumped to the coatinghead and roll coated with a Meyer rod onto a sheet of aluminum foil(about 9 inches wide and about 0.0005 inches thick). After application,the solution/foil are contacted with a Mylar wipe (about 0.002 inchesthick by about 2 inches and by about 9 inches wide--the entire width ofaluminum foil). The wipe is flexibly engaged with the foil (i.e., thewipe merely contacted the foil) to redistribute the solution so as toprovide for a substantially uniform coating. Evaporation of the solvents(i.e., water and isopropanol) via a conventional gas-fired oven providesfor an electrically-conducting adhesion-promoter layer of about 6microns in thickness or about 3×10⁻⁴ grams per cm². The aluminum foil isthen cut to about 8 inches wide by removing approximately 1/2 inch fromeither side by the use of a conventional slitter so as to remove anyuneven edges.

In order to further remove the protic solvent from this layer, the foilis redried. In particular, the foil is wound up and a copper supportplaced through the roll's cavity. The roll is then hung overnight fromthe support in a vacuum oven maintained at about 130° C. Afterwards, theroll is removed. In order to avoid absorption of moisture from theatmosphere, the roll is preferably stored into a desiccator or othersimilar anhydrous environment to minimize atmospheric moisture contentuntil the cathode paste is ready for application onto this roll.

The second preparation of this colloidal solution comprises mixing 25lbs of carbon powder (Shawinigan Black™--available from Chevron ChemicalCompany, San Ramon, Calif.) with 100 lbs of a 25 weight percent solutionof polyacrylic acid (average molecular weight of about 240,000,commercially available from BF Goodrich, Cleveland, Ohio, as Good-RiteK702--contains about 25 lbs polyacrylic acid and 75 lbs water) and with18.5 lbs of isopropanol. Stirring is done in a 30 gallon polyethylenedrum with a gear-motor mixer (e.g., Lightin Labmaster Mixer, modelXJ-43, available from Cole-Parmer Instruments Co., Niles, Ill.) at 720rpm with two 5 inch diameter A310-type propellers mounted on a singleshaft. This wets down the carbon and eliminates any further dustproblem. The resulting weight of the mixture is 143.5 lbs and containssome "lumps".

The mixture is then further mixed with an ink mill which consists ofthree steel rollers almost in contact with each other, turning at 275,300, and 325 rpms respectively. This high shear operation allowsparticles that are sufficiently small to pass directly through therollers. Those that do not pass through the rollers continue to mix inthe ink mill until they are small enough to pass through these rollers.When the mixing is complete, the carbon powder is completely dispersed.A Hegman fineness of grind gauge (available from Paul N. Gardner Co.,Pompano Beach, Fla.) indicates that the particles are 4 to 6 μm in sizewith the occasional presence of 12.5 μm particles. The mixture can bestored for well over 1 month without the carbon settling out orreagglomerating.

When this composition is to be used to coat the current collector, anadditional 55.5 lbs of isopropanol is mixed into the composition workingwith 5 gallon batches in a plastic pail using an air powered shaft mixer(Dayton model No. 42231 available from Granger Supply Co., San Jose,Calif.) with a 4 inch diameter Jiffy-Mixer brand impeller (such as animpeller available as Catalog No. G-04541-20 from Cole Parmer InstrumentCo., Niles, Ill.). Then, it is gear pumped through a 25 μm cloth filter(e.g., So-Clean Filter Systems, American Felt and Filter Company,Newburgh, N.Y.) and Meyer-rod coated as described above.

B. The Cathode

The cathode is prepared from a cathodic paste which, in turn, isprepared from a cathode powder as follows:

i. Cathode Powder

The cathode powder is prepared by combining 90.44 weight percent V₆ O₁₃[prepared by heating ammonium metavanadate (NH₄ ⁺ VO₃ ⁻) at 450° C. for16 hours under N₂ flow] and 9.56 weight percent of carbon (from ChevronChemical Company, San Ramon, Calif. under the tradename of ShawiniganBlack™). About 100 grams of the resulting mixture is placed into agrinding machine (Attritor Model S-1 purchased from Union Process,Akron, Ohio) and ground for 30 minutes. Afterwards, the resultingmixture is dried at about 260° C. for 21 hours.

ii. Cathode Paste

A cathode paste is prepared by combining sufficient cathode powder toprovide for a final product having 45 weight percent V₆ O₁₃.

Specifically, 171.6 grams of a 4:1 weight ratio of propylenecarbonate:triglyme is combined with 42.9 grams of polyethylene glycoldiacrylate (molecular weight about 400 available as SR-344 from SartomerCompany, Inc., Exton, Pa.), and about 7.6 grams of ethoxylatedtrimethylolpropane triacylate (TMPEOTA) (molecular weight about 450available as SR-454 from Sartomer Company, Inc., Exton, Pa.) in a doubleplanetary mixer (Ross No. 2 mixer available from Charles Ross & Sons,Company, Hauppage, N.Y.).

A propeller mixture is inserted into the double planetary mixer and theresulting mixture is stirred at a 150 rpms until homogeneous. Theresulting solution is then passed through sodiated 4A molecular sieves.The solution is then returned to double planetary mixer equipped withthe propeller mixer and about 5 grams of polyethylene oxide (numberaverage molecular weight about 600,000 available as Polyox WSR-205 fromUnion Carbide Chemicals and Plastics, Danbury, Conn.) is added to thesolution vortex formed by the propeller by a mini-sieve such as a 25mesh mini-sieve commercially available as Order No. 57333-965 from VWRScientific, San Francisco, Calif.

The solution is then heated while stirring until the temperature of thesolution reaches 65° C. At this point, stirring is continued until thesolution is completely clear. The propeller blade is removed and thecarbon powder prepared as above is then is added as well as anadditional 28.71 grams of unground carbon (from Chevron ChemicalCompany, San Ramon, Calif. under the tradename of Shawinigan Black™).The resulting mixture is mixed at a rate of 7.5 cycles per second for 30minutes in the double planetary mixer. During this mixing thetemperature is slowly increased to a maximum of 73° C. At this point,the mixing is reduced to 1 cycle per second the mixture slowly cooled to40° to 48° C. (e.g., about 45° C.). The resulting cathode paste ismaintained at this temperature until just prior to application onto thecurrent collector.

The resulting cathode paste has the following approximate weight percentof components:

    ______________________________________                                        V.sub.6 O.sub.13       45 weight percent                                      Carbon                 10 weight percent                                      4:1 propylene carbonate/triglyme                                                                     34 weight percent                                      polyethylene oxide     1 weight percent                                       polyethylene glycol diacrylate                                                                       8.5 weight percent                                     ethoxylated trimethylolpropane triacrylate                                                           1.5 weight percent                                     ______________________________________                                    

In an alternative embodiment, the requisite amounts of all of the solidcomponents are added to directly to combined liquid components. In thisregard, mixing speeds can be adjusted to account for the amount of thematerial mixed and the size of the vessel used to prepare the cathodepaste. Such adjustments are well known to the skilled artisan.

In order to enhance the coatability of the carbon paste onto the currentcollector, it may be desirable to heat the paste to a temperature offrom about 60° C. to about 130° C. and more preferably, from about 80°C. to about 90° C. and for a period of time of from about 0.1 to about 2hours, more preferably, from about 0.1 to 1 hour, and even morepreferably from about 0.2 to 1 hour. A particularly preferredcombination is to heat the paste at from about 80° C. to about 90° C.for about 0.33 to about 0.5 hour.

During this heating step, there is no need to stir or mix the pastealthough such stirring or mixing may be conducted during this step.However, the only requirement is that the composition be heated duringthis period. In this regard, the composition to be heated has a volumeto surface area ratio such that the entire mass is heated during theheating step.

A further description of this heating step is set forth in U.S. patentapplication Ser. No. 07/968,203 filed Oct. 29, 1992 and entitled"METHODS FOR ENHANCING THE COATABILITY OF CARBON PASTES TO SUBSTRATES",which application is incorporated herein by reference in its entirety.

The so-prepared cathode paste is then placed onto the adhesion layer ofthe current collector described above by extrusion at a temperature offrom about 45 to about 48° C. A Mylar cover sheet is then placed overthe paste and the paste is spread to thickness of about 90 microns (μm)with a conventional plate and roller system and is cured by continuouslypassing the sheet through an electron beam apparatus (Electro-curtain,Energy Science Inc., Woburn, Mass.) at a voltage of about 1.75 kV and acurrent of about 1.0 mA and at a rate of about 1 cm/sec. After curing,the Mylar sheet is removed to provide for a solid cathode laminated tothe aluminum current collector described above.

c. Electrolyte

The electrolyte may be prepared by first combining at room temperature56.51 grams of propylene carbonate, 14.13 grams triglyme, and 10.00grams of urethane acrylate (available as Photomer 6140 from HenkelCorporation, Coating and Chemical Division, Ambler, Pa.) untilhomogeneous. The resulting solution is passed through a column of 4 Asodiated molecular sieves to remove water and then is mixed at roomtemperature until homogeneous.

To the dried propylene carbonate, triglyme, and urethane acrylate areadded 7.56 grams of the acrylic alkoxy substituted silane of Formula Iwhere z is 6, and R₁, R₂, and R₃ are methoxy. To this stirred solutionare added 2.56 grams of polyethylene oxide film-forming agent (weightaverage molecular weight of about 600,000 available as Polyox WSR-205from Union Carbide Chemicals and Plastics, Danbury, Conn.).

In one embodiment, the polyethylene oxide film-forming agent is added tothe solution via a mini-sieve such as a 25 mesh mini-sieve commerciallyavailable as Order No. 57333-965 from VWR Scientific, San Francisco,Calif..

Once the polyethylene oxide and the acrylic alkoxy substituted silaneare dispersed and dissolved, the mixture is then thoroughly mixed byheating until a temperature of about 60° to 65° C. is reached which aidsin the dissolution of the film-forming agent. The solution is cooled toa temperature of between 45° and 48° C., a thermocouple is placed at theedge of the vortex created by the magnetic stirrer to monitor solutiontemperature, and then 9.24 grams of LiPF is added to the solution over a120 minute period while thoroughly mixing to ensure a substantiallyuniform temperature profile throughout the solution. Cooling is appliedas necessary to maintain the temperature of the solution between 45° and48° C.

This solution is then degassed to provide for an electrolyte solutionwherein little, if any, of the LiPF₆ salt decomposes.

The acrylic alkoxy substituted silane may be prepared by initiallyreacting chlorotrimethoxy silane with 1,6-hexanediol in a dilute aproticsolvent with the loss of HCl gas to form: ##STR12## and this compoundsubsequently is reacted with acryloyl chloride to form the monomer ofFormula I.

The resulting mixture contains the following weight percent ofcomponents:

    ______________________________________                                        Propylene carbonate 56.51 weight percent                                      Triglyme            14.13 weight percent                                      Urethane acrylate   10.00 weight percent                                      (Photomer 6140)                                                               LiPF.sub.6           9.24 weight percent                                      Polyethylene oxide   2.56 weight percent                                      Acrylic alkoxy substituted                                                                         7.56 weight percent.                                     silane                                                                        ______________________________________                                    

Optionally, solutions produced as above and which contain the recitedcomponents and the LiPF₆ salt are filtered to remove any solid particlesor gels remaining in the solution. One suitable filter device is asintered stainless steel screen having a pore size between 1 and 50 μmat 100% efficiency.

Alternatively, the electrolyte solution can be prepared in accordancewith a mixing procedure which employs the following steps:

1. Check the moisture level of the urethane acrylate. If the moisturelevel is less than 100 ppm water, proceed to step 2. If not, then firstdissolve the urethane acrylate at room temperature, <30° C., in thepropylene carbonate and triglyme and dry the solution over sodiated 4Amolecular sieves (Grade 514, 8-12 Mesh from Schoofs Inc., Moraga,Calif.) and then proceed to step 4.

2. Dry the propylene carbonate and triglyme over sodiated 4 A molecularsieves (Grade 514, 8-12 Mesh from Schoofs Inc., Moraga, Calif.).

3. At room temperature, <30° C., add the urethane acrylate to thesolvent prepared in step 2. Stir at 300 rpm until the resin iscompletely dissolved. The solution should be clear and colorless.

4. Dry and then sift the polyethylene oxide film-forming agent through a25 mesh mini-sieve commercially available as Order No. 57333-965 fromVWR Scientific, San Francisco, Calif. While stirring at 300 rpm, add thedried and pre-sifted polyethylene oxide film-forming agent slowing tothe solution. The polyethylene oxide film-forming agent should be siftedinto the center of the vortex formed by the stirring means over a 30minute period. Addition of the polyethylene oxide film-forming agentshould be dispersive and, during addition, the temperature should bemaintained at room temperature (<30° C.).

5. After final addition of the polyethylene oxide film-forming agent,stir an additional 30 minutes to ensure that the film-forming agent issubstantially dispersed. Then add the acrylic alkoxy substituted silanewith stirring.

6. Heat the mixture to 68° to 75° C. and stir until the film-formingagent has melted and the solution has become transparent to light yellowin color. Optionally, in this step, the mixture is heated to 65° to 68°C.

7. Cool the solution produced in step 6 and when the temperature of thesolution reaches 40° C., add the LiPF₆ salt very slowly making sure thatthe maximum temperature does not exceed 55° C.

8. After the final addition of the LiPF₆ salt, stir for an additional 30minutes, degas, and let sit overnight and cool.

9. Filter the solution through a sintered stainless steel screen havinga pore size between 1 and 50 μm at 100 percent efficiency.

At all times, the temperature of the solution should be monitored with athermocouple which should be placed in the vortex formed by the mixer.

Afterwards, the electrolyte mixture is then coated by a conventionalknife blade to a thickness of about 50 μm onto the surface of thecathode sheet prepared as above (on the side opposite that of thecurrent collector) but without the Mylar covering. The electrolyte isthen cured by continuously passing the sheet through an electron beamapparatus (Electrocurtain, Energy Science Inc., Woburn, Mass.) at avoltage of about 1.75 kV and a current of about 1.0 mA and at a conveyorspeed setting of 50 Which provides for a conveyor speed of about 1cm/sec. After curing, a composite is recovered which contained a solidelectrolyte laminated to a solid cathode.

D. Anode

The anode comprises a sheet of lithium foil (about 76 μm thick) which iscommercially available from FMC Corporation Lithium Division, BessemerCity, N.C.

E. The Solid Electrolytic Cell

A sheet comprising a solid battery is prepared by laminating the lithiumfoil anode to the surface of the electrolyte in the sheet produced instep C above. Lamination is accomplished by minimal pressure.

Without being limited thereby, it is believed that the incorporation ofrecurring units derived from the silane acrylate of the invention intothe polymer backbone of the solid polymeric matrix provides theadvantages discussed hereafter.

By providing up to three reactive sites on the Si atom it is possible toprovide up to two additional pendant groups compared with, for example,a simple acrylate. Such pendant groups can facilitate enhancedconductivity within the solid, solvent-containing electrolyte.

Additionally, the pendant groups (as defined) allow the solid polymericmatrix to "open up", such that the polymer chains are more spread out.This gives the polymer greater flexibility and swellability. Ifcross-link density of the polymer matrix is too high, resulting in atightly bound polymer, one or more of the arms (i.e., pendant silanegroups) may become entangled in the polymer network, but the remainingarm or arms is (are) still available for coordination.

By comparison, typical acrylic groups provide only one pendant group orarm for coordinating, and if it becomes entangled, then no pendant groupis available for Li transport in those instances when the substituentson the pendant group could otherwise participate in this function.

Although the invention has been described with preferred embodiments, itis to be understood that variations and modifications may be resorted toas will be apparent to those skilled in the art. Such variations andmodifications are to be considered within the purview and scope of theclaims appended hereto.

I claim:
 1. A compound represented by Formula I: ##STR13## where z is 3to 10, and R₁ R₂, and R₃ are independently selected from the groupconsisting of (a) --Y--CH₂ CH₂)_(x) H where x is an integer of 1 to 20,Y is O, S, NH, or NR where R is an alkyl group having 1 to 10 carbonatoms, (b) an alkyl substituent having 1 to 6 carbon atoms, (c) analkoxy group having 1 to 6 carbon atoms, (d) --O--R₄ --O)_(p) R₅ whereR₄ is an alkylene group having 1 to 4 carbon atoms, R₅ is an alkylsubstituent having from 1 to 4 carbon atoms, and p is an integer from 1to 4, (e) --SR₆ where R₆ is an alkyl substituent having from 1 to 6carbon atoms, (f)--NH₂, (g)--NHR₇ where R₇ is an alkyl substituenthaving 1 to 6 carbon atoms, (h)--NR₈ R₉ where R₈ and R₉ areindependently chosen from alkyl substituents having 1 to 6 carbon atoms,##STR14## where y is 3 to 10, and R₁₁ is H or CH₃.
 2. A compoundaccording to claim 1 wherein R₁, R₂, and R₃ are methoxy.
 3. A compoundaccording to claim 1 wherein R₁, R₂, and R₃ are ##STR15##
 4. A compoundaccording to claim 1 wherein R₁, R₂, and R₃ are --O--CH₂ CH₂ --O)₃ CH₃.5. A single phase, solid, solvent-containing electrolyte whichcomprises:a solid polymeric matrix; an inorganic ion salt; and asolvent;wherein said solid polymeric matrix is obtained by polymerizingan organic monomer represented by Formula I: ##STR16## where z is 3 to10, and R₁, R₂, and R₃ are independently selected from the groupconsisting of (a) --Y--CH₂ CH₂)_(x) H where x is an integer of 1 to 20,Y is O, S, NH, or NR where R is an alkyl group having 1 to 10 carbonatoms, (b) an alkyl substituent having 1 to 6 carbon atoms, (c) analkoxy group having 1 to 6 carbon atoms, (d)--O--R₄ --O)_(p) R₅ where R₄is an alkylene group having 1 to 4 carbon atoms, R₅ is an alkylsubstituent having from 1 to 4 carbon atoms, and p is an integer from 1to 4, (e)--SR₆ where R₆ is an alkyl substituent having from 1 to 6carbon atoms, (f)--NH₂, (g)--NHR₇, where R₇ is an alkyl substituenthaving 1 to 6 carbon atoms, (h)--NR₈ R₉, where R₈ and R₉ areindependently chosen from alkyl substituents having 1 to 6 carbon atoms,##STR17## where y is 3 to 10, and R₁₁ is H or CH₃.
 6. A single phase,solid solvent-containing electrolyte according to claim 5 where R₁, R₂,and R₃ of said solid polymeric matrix are methoxy.
 7. A single phase,solid, solvent-containing electrolyte according to claim 5 where R₁, R₂,and R₃ of said solid polymeric matrix are ##STR18##
 8. A single phase,solid, solvent-containing electrolyte according to claim 5 where R₁, R₂,and R₃ of said solid polymeric matrix are--O--CH₂ CH₂ --O)₃ CH₃.
 9. Asingle phase, solid, solvent-containing electrolyte according to claim 5where said inorganic ion salt is a sodium, lithium, or ammonium salt ofa less mobile anion of a weak base having a large anionic radius.
 10. Asingle phase, solid, solvent-containing electrolyte according to claim 9where said inorganic ion salt is selected from the group consisting ofLiPF₆, LiClO₄, NaClO₄, LiCF₃ SO₃, and LiBF₄.
 11. A single phase, solid,solvent-containing electrolyte according to claim 5 where said solventis a mixture of propylene carbonate and triglyme.
 12. An electrolyticcell which comprises:(i) an anode comprising a compatible anodicmaterial; (ii) a cathode comprising a compatible cathodic material; and(iii) interposed therebetween a single phase, solid, solvent-containingelectrolyte which comprises: a solid polymeric matrix; an inorganic ionsalt; and a solventwherein said solid polymeric matrix is obtained bypolymerizing an organic monomer represented by the Formula I: ##STR19##where z is 3 to 10, and R₁, R₂, and R₃ are independently selected fromthe group consisting of (a)--Y--CH₂ CH₂)_(x) H where x is an integer of1 to 20, Y is O, S, NH, or NR where R is an alkyl group having 1 to 10carbon atoms, (b) an alkyl substituent having 1 to 6 carbon atoms, (c)an alkoxy group having 1 to 6 carbon atoms, (d)--O--R₄ --O)_(p) R₅ whereR₄ is an alkylene group having 1 to 4 carbon atoms, R₅ is an alkylsubstituent having from 1 to 4 carbon atoms, and p is an integer from 1to 4, (e)--SR₆, where R₆ is an alkyl substituent having from 1 to 6carbon atoms, (f)--NH₂, (g)--NHR₇, where R₇ is an alkyl substituenthaving 1 to 6 carbon atoms, (h) --NR₈ R₉, where R₈ and R₉ areindependently chosen from alkyl substituents having 1 to 6 carbon atoms,##STR20## where y is 3 to 10, and R₁₁ is H or CH₃.
 13. An electrolyticcell according to claim 12 wherein R₁, R₂, and R₃ are methoxy.
 14. Anelectrolytic cell according to claim 12 wherein R₁, R₂, and R₃ are##STR21##
 15. An electrolytic cell according to claim 12 wherein R₁, R₂,and R₃ are --O--CH₂ CH₂ --O)₃ CH₃.
 16. An electrolytic cell according toclaim 12 wherein said inorganic ion salt is a sodium, lithium, orammonium salt of a less mobile anion of a weak base having a largeanionic radius.
 17. An electrolytic cell according to claim 16 whereinsaid inorganic ion salt is selected from the group consisting of LiPF₆,LiClO₄, NaClO₄, LiCF₃ CSO₃, and LiBF₄.
 18. An electrolytic cellaccording to claim 12 wherein said solvent is a mixture of propylenecarbonate and triglyme.
 19. An electrolyte according to claim 5 whereinsaid organic monomer represented by Formula I is copolymerized with aco-monomer which is also represented by Formula I.
 20. An electrolyticcell according to claim 12 wherein an organic monomer represented byFormula is copolymerized with a co-monomer which is also represented byFormula I.